https://odan.github.io/2017/08/13/xampp-replacing-mariadb-with-mysql.html

XAMPP - Replacing MariaDB with MySQL

As of XAMPP 5.5.30 and 5.6.14, XAMPP ships MariaDB instead of MySQL. MariaDB is not 100% compatible with MySQL and can be replaced with the “orginal” MySQL server.

Requirements
Windows
XAMPP for Windows
Administrator privileges to restart Windows services
Backup
Backup the old database into a sql dump file
Stop the MariaDB service
Rename the folder: c:\xampp\mysql to c:\xampp\mariadb
Installation
Download MySQL Community Server: https://dev.mysql.com/downloads/mysql/
Click: Looking for the latest GA version?
Select Version: 5.7.25
Select Operating System: Microsoft Windows
Select OS Version: Windows (x86, 32-bit)
Scroll down to ZIP Archive and click Download.
Create a new and empty folder: c:\xampp\mysql
Extract mysql-5.7.25-win32.zipp to: c:\xampp\mysql
Create a new file: c:\xampp\mysql\bin\my.ini and copy this content:
[mysqld]
# Set basedir to your installation path
basedir=c:/xampp/mysql

# Set datadir to the location of your data directory
datadir=c:/xampp/mysql/data

# Default: 128 MB
# New: 1024 MB
innodb_buffer_pool_size = 1024M
Initializing the data directory
Copy the old data directory from c:\xampp\mariadb\data to c:\xampp\mysql\data

Start the MySQL server. You can use the XAMPP Control Panel (MySQL > Start) to start the MySQL service.

Repair all corrupted tables in the c:\xampp\mysql\data directory. Press ENTER if your password is empty.

cd c:\xampp\mysql\bin
mysqlcheck.exe -u root -p --auto-repair --all-databases
Update structure to latest version:

mysql_upgrade.exe -u root -p --force
Check the tables for errors:

mysqlcheck.exe -u root -p --check --all-databases
Notice: If you don’t want to copy and migrate the old data directory, you can create a fresh directory with this command:

c:\xampp\mysql\bin>mysqld.exe --initialize-insecure --basedir=c:\xampp\mysql --datadir=c:\xampp\mysql\data
Finished

Known issues
Questions
I can’t start or stop mysql using the XAMPP control panel button
The XAMPP control panel is crashing while shutting down
Answers
Make sure you have installed the 32-bit version of MySQL. The MySQL 64-bit version is not compatible with the XAMPP Control Panel.
This setup is not testet with MySQL 8.x
Try to fix the directory permissions with this batch script